Coated fabric



Patented June 29. 1943 UNITED STATES- PATENT orrlce jzszasss Franklin '1'. Peters, Wilmington, Del, aulgnor to E. I. du Pont deNel'nourl & Company. Wilmington, Del, a corporation of Delaware 'No Drawing. Application February :1, 1941, Serial No. 279,949

6 Claims. ((1117-88) This invention relates to improvements in coated fabrics and moreparticula-rly to artificial l ather in which a cellulose derivative film is esially anchored to the base fabric.

Cellulose derivative coatings such as cellulose nitrate, cellulose acetate, .ethyl cellulose, cellulose aceto-propionate, etc; have been used extensively as a protective coating for sheet ma-' terials such as woven fabrics, unwoven fabrics, paper, metal. etc. The flexible materials are often used as upholstery material, pocketbook material, and the like where they receive repeated flexings. The products thus far produced=are not entirely satisfactory. to the prior art material is that the bond between the cellulose derivative coating and the flexible base material is often broken during repeated fiexings. This is particularly true of cellulose derivative coatings on a continuous filament fabric due to, the absence of the short protruding fibers referred to as nap. In the case of a cotton fabric the nap extends up into the coating and helps bond the coating to the fabric. Also, the cellulose derivative coatings, per'se, are subiect on aging to brittleness, decomposition, fra- One primary objection a test test was employed for the determination of the bond between the dried coating and the base sheet material. This test is described as follows:

The anchorage of a cellulose derivative film to a base fabric is determined by measuring the force required to strip a unit width of dry film from the base fabric. A piece of cotton sheeting (running 3.60 yards per pound per 40 inch width) measuring about 10 inches x 13 inches, is given a plurality of coats of a cement comprising an unpigmented. plasticized cellulose derivative dispersion and allowed to dry after each successive coat. The cellulose derivative and plasticizer employedin the cement are usually the same as that employed in the film of the material to be' tested. Before the dispersing medium is allowed to evaporate in the final coat the wet cement is gility and cracking. Further, the nitrocellulose-- coatings when applied on a textile base, upon decomposition give of! acid bodies which cause severe tendering of the textile fabric.

A primary object of this invention therefore is the provision of a cellulose derivative coated sheet having none of the disadvantages mentioned above and whichis economical to produce. A further object of this invention is the provision of essentially a cellulose derivative coated sheet material having an improved bond of the coatingto the sheet material and improved resistance of the coating to cracking when subiected to repeated flexing.

' A still further object is the provision of an essentially cellulose nitrate coated fabric in which the coating contacting the fabric is resistant to decomposition and does not resultin the tendering of the base fabric upon aging and prolonged usage. 2 I

Other objects will appear hereinafter as the description of the invention proceeds.

These objects are accomplished by applying a' substrata layer of a coating composition comprising a. synthetic linear polyamlde directly on a suitable base sheet material and applying dlrectly over the said polyamide coating a cellulose derivative coating composition.

The following examples are given by way of illustration and not limitation and the inventionis not to be limited except as defined in the appended claims.

In the examples the anchorage of the dried coating to the base fabric is referred to as the pounds pull to separate the coating from firmly pressed upon the dry coating of the materlal to be tested and the composite assembly is thoroughly dried. The warp threads in each fabric are arranged in parallel relation. Two samples 2 inches x 8 inches which aretapered at one end are cut from the dried composite sample in. such a manner that the 8 inch dimension is parallel to warp threads. The composite fabrics at the tapered end arc separated and pulled apart for a distance of 2 inches, care being taken to have the coating of the original material adhereto the reinforcing fa'bric cemented thereto. beginning of the separation at the tapered end is assisted by wetting the tip of the tapered portion in a suitable solvent for the cellulose derivative.

One part of the separated sample is clamped in the upper Jaws of a standard Scott tensile strength tester and the other in the lower laws. The Scott tensile strength tester is well known in the textile art and its description does not appear to be necessary. The weight is removed from the pendulum lever of the tester, which is then connected to the recorder (with chart) by means of a connecting rod. The pawl on the ratchet of the tester is disengaged during the test. The laws which are 3 inches apart at the start of the test are separated at the rate of 12 inches per minute. As the coating is separated from the original fabric, the degree of anchorage is registered onthe" recorder chart in the pounds pull required to separate the film from the base fabric. It is necessary that the fabrics separate cleanly when being pulled apart. If there is a tendency for the fabric to unravel at the side of the test piece this must be corrected either by gently pulling the threads away or by cutting Tee" 1 Eximru: I

A woven cotton textile fabric, having a sateen weave and running 1.12yards per pound per 53 inch width, dyed a suitable color, was given one knife application of the following composition:

2 Anchor composition Per cent Synthetic linear polyamide 33 Solvent mixtur 67 The solvent mixture consisted of seven vol--- umes of toluene and three volumes of denatured alcohol (formula 23). polyamide was derived from hexamethylene diammonium adipate (85%) and 15% of an equimolecular mixture of ethylene glycol and adipic acid. Approximately three ounces of the above composition were applied per yard per 53 inch width, which corresponds to approximately one ounce per yard per 53 inch width ofthe nonvolatile constituent, by means of a coating apparatus disclosed in U. S. Patent 2,107,276, which issued February 8, 1938, to W. '1'. Anderson. The volatile solvents were dissipated by passing the coated fabric through a heated drying chamber such as disclosed in U. S. Patent 2,107,275, which issued February 8,1938, to W. T. Anderson et al. A plurality of coats of the following composi: tion were applied directly over the anchor coat:

Cellulose derivative coating composition Per cent Cellulose nitrate 12.3 Pigments v 12.9 Blown cottonseed oil 26.4 Denatured ethyl alcohol (23 formula).. 24.2 Ethyl aceta 24.2

The synthetic linear 130 [161154 5 pounds.

prepared was subjected to the standard anchorage test. The average of two test samples indicated the anchorage of the dried cellulose derivative coating to'the base fabric to be 10.9 pounds.

'Exmu 111 A coated fabric which ,was the same as that described in Example I was prepared by the method set forth in Example 1, except that the anchor composition consisted of the following:

Anchor composition Per cent Polyamide 21.0 1,12 -diphenyloloctadecane 8.4 Butyl phthalyl butyl glycollate 5.6 Solvent mixture 65.0

The solvent mixture in the above composition consistedof 9 volumes of denatured ethyl alcohol (23 formula) and one volume of water. The polyamide used was'derlved from hexamethylene diammonium adipate, hexamethylene diammoniuln sebacat'e'and caprolactam in the ratio of 40:30:30.

The coated fabric thus prepared was subjected to the standard anchorage test, which indicated the anchorage of the dried film to the base fabric Elmira: IV

Eximrnn V A woven fabric having a sateen weave and conslsting of continuous filaments of regenerated celin connection with the application of the :anchor composition. At the intermediate stage 0.! coating, that is, when approximately one-half of-the total amount of coating was applied, the coated fabric was given a heat and pressure treatment by passing through conventional heated embossingrollers one of which has a shallow design referred to in the trade as Shiver. grain, to compress the coating and assist in anchoring the coating to the base fabric.

For commercial production it is customary to apply a finishing composition such as an unplzmented. unplasticized cellulose nitrate dispersion to obtain a glossy finish, or a high y p smented gemllsulllo e nitrate composition to obtain a dull lulose of uniform denier such as described in U. 5. Patent 2,083,252, granted to Bradshaw 8: H011, was given one knife application of thafollowing:

Anchor composition Per cent Polyamide 15 Solvent mixtur 85 to approximately. 1,0:ounce per yard per The material described above was subjected to the standard anchorage test described above, whichshow'edthe anchorage of the coating to thebasefabric to-be 14.2pounds.

a control sample similar to transcribed in Example I was prepared in which the some materlals. and method were except that thepolyamide anchor coat was omitted, which was replaced by an equal weight of the cellulose derivative composition. The entire coating .con-. sisted of the cellulose derivative coating compost tion described in Example I. The material thus The solvent mixture consisted of volumes of ethyl alcohol.j (2B formula) and 10 volumes of water. The polyamide used was the came as that used in Example 111. Approximat'ely'sevenounces of the above composition were applied per yard per 53 inch width, whichcorresponds width of non-volatile components.

A plurality of coats of the following composltlon' were applied directly over the anchor coat.

Cellulose derivative coatiiw I Percent Cellulose. nitrate "-10.0: Colored L- 19.78 emoloil modified glycerol sebacate'....--- icso Ethyl acetate... 31.56 Ethyl alcohol 31.56

Suiiicient coats of the above composition were i applied to deposit approximately 28 ounces per yard per 53 inch width, which corresponds to 10.4 olmces per' yard per 53 inch width. Both the anchor coat and cellulose derivative coatlnl 53 men;

' Water position having the following formula:

asaaoss composition were applied anddried by the means described in Example I.

The average of two test samples prepa ed as described above showed an anchorage of pounds as determined by the standard anchorage test. i

A control sample prepared at the same time as Example V, using same materials and the. same method as described in Example V,

except that the polyamide coat was omitted, which. was replaced by an .equal weight of the cellulose derivative composition.

, The anchorage of the dried film to the base fabric as determined by the standard anchorage test was 3.5 pounds.

Exsuru VII Example III a sateen fabric was coated-as describsqpin' Example I with an anchor coat of following composition:

Per cent Polyamide 22.25

N beta hydroxyethyl o-methoxy-benzamide v 27.75 Denatured ethyl alcohol (213 formula) 37.60 12.40

The polyamide used was that derived from 60 parts of hexamethylene diammonium adipate and 40 parts of caprolactam.

Next a plurality of coats of nitrocellulose com Per cent Cellulose nitra 12.3 Pi ments 12,9 Blown cottonseed oil.. 26l4 Ethyl alcohol (23A iormula)' -s 24.2, Ethyl ace 24.2

was applied directly over the anchor coat in the same manner and amount as described in Example I. The product gave value of 15,000 flexings before failure in the Schiltknecht test as described below.

Exsmm: VIII Y the structure of these polyamides,-

A product prepared as described in Example VII but replacing the polyamide anchor coat with the following composition:

Per cent Cellulose nitr 10.7 55% castor oil modified alkyd resin 24.4 Butyl acetate 15.0 Toluol 16.2 Ethyl acetate 16.8 Ethyl alcohql (23A formula) 16.9

failed in the Schiltknecht flextest at 800 flexes.

The Schiltknechtfiex test is conducted on a commercial machine built for measuring ,the crack resistance of coatings applied on fabric bases. The machine comprises a casing to which is cast a guide for a vertically reciprocating crossarm. The cross-armis formed or shaped of four radiating members; at the extremities of each is attached a vertical cylinder, sopositioned that separate test pieces may be clamped at either end of the cylinder. The main body of the casting is provided with eight fixed vertical cylinders (four above and four below) ofthe same dersisiflandatfullcomprusiontheminimmn clearance is One end of'the. -lllhple (3" x 1%") is clamped around the fi'xed'cylinder: the otherendiscl'smpedaruundthemciprocating cylinder positionedinnnediateiy w,

to form a hollow tube. 'Iheredproeation f the movable cylinder causes a flexing in the'test sample.

Summary of anchordac tests Andmrage M Example I lysmide anchor coat) Example (control for Example I-no polyamide anchor coat) lyamide anchor coat) Example IV control for Example IXI-no polyamide anchor 0000-. Example V (polyamide anchor cost) xample VI (control for Example V-no anchor coat) Summary of Schiltknccht fie: tests Increase over control Flexes 15, one

Example'VII (polyamide anchor coat) Example VIII (control for Example VII- no polyamide anchor coat) Per cmt 1775 number of carbon atoms in the segments of the chain separating the amide groupsis at least two. Accordingly, in this specification and the claims appended thereto, the expression, synthetic linear polyamide, is to be understood as applyins to po yamides not only belonging to types described in the aforesaid patents, but also coming within the limitations pointed out.in this paragraph. I

The term polyamide" 'as used above is not limited to polymers derived solely from polyamide-forming reactants. It includes also polymers obtained by including with the polyamideforming reactants from which the po mers are prepared, other polymer-forming compositions, e. g., hydroxy acids, glycol-dibasic acid mixtures,

and amino alcohol-dibasic acid mixtures. The

diameter and in the same vertical axes as the cylinders described on the reciprocating cross-arm.

At the-time the -testsample is clamped around the fixed and reciprocatingcylinders the maxi-'- mnm clearance between the superposed cylinpolymers obtained in this manner can still be referred to as polyamides since'they contain amide groups in the main polymer chain and unmodified polyamides. v

Ingeneral it is desirable to use an interpolyamide as theanchor coat rather than a simple polyamide. since the interpolyamides have better solubility characteristics and greater pliability. In addition to the interpolyamides described in the foregoingezamples, thefollowing are also very useful: the interpolyamide derived from 3 hcxamethylene adipate and decapossess many ofthe desirable properties of the adipamide and polytriglycol adipamide or poly-" N,N'-dimethyl-hexamethylene adipamide are also useful.

As indicated in the examples the polyamide anchor coating may contain plasticizers. Ex-

amples of additional. useful plasticizers include sulfonamides, such as N-ethylamylbenzene sulfonamide; phenols such as diamyi phenol and octyl phenol; salicylamides; and other known plasticizers for the polyamides, mixed, if desired, with other materials of known softening action for the polyamides and nitrocellulose, such as castor oil or derivatives thereof, high boiling aromatic or aliphatic esters, and the like. Pig'- ments, resins fillers and flattening agents. can also be incorporated in the anchor coat although these are usually added to the cellulose derivative coat. q

While the preferred embodiment of the invention as described in the examples employs-a cellu-.

lose nitrate coating for the major portion of film applied on the base material, it is to be understood that other cellulose esters may be employed such as cellulose acetate, cellulose propionate and cellulose butyrate, as well as cellulose ethers such as ethyl cellulose and benzyl cellulose; also mixed esters ands-ether esters, such as, e. g., cellulose aceto-propionate and cellulose acetobutyrate. In

the claims the term cellulose derivative" is used to refer to the water-insoluble film-forming cellulose derivatives, such as cellulose esters. cellulose ethers, and mixed cellulose esters and not to non-film-forming cellulose derivatives such as glucose and carbondioxide.

The base material for the system of coatings herein described is. not limited to woven cotton textile fabrics, since other flexible base materials are suitable such as unwoven cotton fabrics,

generated cellulose, paper, woven and unwoven glass fabrics and fabrics made from cellulose derivative yarns such as viscose and cellulose ace-' tate. In the use of a cellulose derivative fabric as the base material the choice of solvents employed in the anchor composition must be such that they do not dissolve the individual threads of the base fabric. Polyamide fabrics may be employed as the base material in which case the polyamide fabric must have a solubility different from that of the polyamide employed in the anchor composition. Y

In Example-I, 1.0 dry ounce of-the polyamide anchor coat was applied to one yard ofbase fabric 53 inches wide. -Thls corresponds to .7

ounce of dry coating persquare yard. Any quantities of the polyamide anchor coat less than .4 ounce ondry coating per square yard are insufficient to accomplish the outstanding advantages of the invention. Quantities of the polyamide anchor coat greater than 1.5 ounces dry coating per square yard do not result'in any appreciable increase in the anchorage of the composite film.

The products produced in accordance with this invention will find extended use wherever plain or embossed cellulose derivative coated products have been used and where improved anchorage of the cellulose derivative coating is desired. It is particularly useful in the manufacture of coated fabrics used for upholstery material, ladies pocketbooks, drawsheets for rotary type printing presses, and bookbinding material.

It will be evident from the foregoing tests that an outstanding advantage of the material produced in accordance with this invention is the production of cellulose derivative coated fabrics having improved anchorage of the coating to the fabric, in which case the superior bond of the coating to the fabric is not impaired during aging and prolonged use of the material. A further advantage is the provision of an anchoring composition for cellulose derivative coated fabrics, which is not subject to decomposition upon aging and does not cause tendering of the base fabric. A still further advantage is the provision of an economical methodof producing a cellulose derivative coated fabric having improved anchorage of the dried coating to the base fabric and improved resistance tofrepeated flexing.

It is apparent that many'widely diflerent embodiments of this invention may be made without departing from the spirit and scope thereof, and therefore it is not intended to be limited except as indicated in the appended claims.

I claim:

1. A coated fabric comprising a base fabric having firmly anchored thereto a thin polyamide coating weighing .4 to 1.5-ounces per square yard, a continuous cellulose derivative coating weighing more than 1.5 ounces per square yard firmly anchored to said polyamide coating, and said coated fabric being characterized by the improved bond of the composite coating to said base fabric.

2. Product of claim 1 in which the polyamide is an interpolyamide.

3. Product of claim'l in which the cellulose derivative 'iscellulose nitrate.

4. Process of preparing acoated fabric of improved bond of the coating to the fabric which comprises applying suflicient dispersion of a polyamide in a volatile solvent to deposit .4 to 1.5 ounces of non-volatile ingredients per square yard, removing thevolatile solvents, applying to" the drycoated fabric a cellulose derivative dissolved in volatile solvents, and removing the volatile solvents, thereby producing a smooth continuous cellulose derivative surface film.

5. Process of claim 4 m which the polyamide is an interpolyamide.

A 6. Process of claim 4 in which the ,ceilulose derivative is cellulose nitrate. 

